Someone has to give young people a chance, says ex-prisoner and founder of Laces, Charles Young. Photograph: Martin Godwin for the Guardian

Charles Young, arriving smartly dressed at his office in south London's Blackheath, is the epitome of respectability. He straightens the collar on his black leather coat, under which is a crisp white shirt. Young, who is fast becoming one of London's most well-known ex-offenders, finds it hard to take a compliment. "Christ, black coat and white shirt, I look like a screw," he says with a toothy laugh.

It has been 17 years since Young'slast stretch inside, six months in a single cell at Elmley prison in Kent. With over 40 convictions for robbery, fraud and burglary, he clocked up around 15 years behind bars between the ages of 19 and 40. Since his release, and inspired by a television programme he saw inside about an ex-con in Glasgow talking to schoolchildren about jail, Young has used his experiences of prison life to steer young people who may idealise and glamorise the criminal lifestyle towards a more fulfilling existence.

He conveys the brutality of prison life through presentations he takes to youth clubs, schools, colleges and, most recently, a naval college, during which an "inmate" sits locked in a mocked-up cell on a stage while Young hammers home what prison is really like. "Inmates" have included a former drug dealer, a vicar and a magistrate. Young shouts, uses raw language and doesn't pull any punches, and by the time his talk is over, some of the hardest-looking, most defiant kids look visibly shaken.

Young has been delivering his "prison's not worth it" message on a shoestring since 1995. Now his efforts are starting to bear fruit. Last year, Young secured £30,000 of Home Office funding for his Laces (London Anti-Crime Education Scheme) project. A community interest company, Laces helps to educate young people at risk of offending about the realities of prison, the consequences of crime and how to make changes to avoid the wrong path.

Respect

Analysis conducted for Young by Mango Communications calculated that in the 10 years to 2005, the project had made 2,000 presentations to young people, and deterred 1,290 potential offenders, thereby saving the public an estimated £6.2m in criminal damage and the criminal justice system approximately £1.2m.

But Young wants to do more. "I still feel so frustrated," he says. "There are people out there [in the criminal justice system] who have never been to prison and who talk to young offenders like they understand them, but they don't. You need to be patient and understanding, but a lot of people alienate these youngsters. You need to show respect to them, give respect to teach respect, and lots of these kids don't respect anyone or anything because they have never had any respect themselves.

"I saw a kid who resisted a caning being whipped when I was at school, and the modern-day equivalent is a teacher with a face contorted with anger jabbing a finger right into a kid's face. That just makes them feel more hopeless and useless. When I see these kids with all the attitude, wanting attention and recognition but not knowing how to get it legitimately, it's like seeing myself at that age."

Young grew up in the London borough of Greenwich in a big family with parents who he feels did not encourage him enough.

"They never pushed me to achieve," he recalls. "I was the second fastest swimmer in the whole of London, but they never ever encouraged me, even though I could have probably been Olympic standard. My mum always was very critical. Kids need to be coached and helped to develop, and that's what I try to do for the kids I work with. I'm a bit of a surrogate parent, giving them the care and support I never had."

Perhaps Young's biggest success story is a 19-year-old man, Jason, a former drug dealer who was recently referred to Laces by a crown court judge in Woolwich, south-east London. Jason has been crime-free ever since, has held a job down for a year, is in a steady relationship and has a baby named Lacey as a tribute to the project that turned his life around.

Young is incredibly proud of Jason and admits that when the judge agreed to revoke the youth offending team order and entrust Young to mentor Jason and keep him out of trouble, his eyes filled with tears. "I knew Laces was going to be a success and that one day this would happen, but it was still a big moment," Young says.

He has since been asked to address a group of six crown court judges about his work and a London probation team recently invited him to work with a newly released high-profile lifer who wants to turn away from crime for good.

So what does Young make of the government's plans for probation and prisons? Young says that while he is in favour of justice secretary Ken Clarke's prison and sentencing reforms, he does not believe that shorter sentences are going to reduce reoffending. "Recidivism is still high because most prisoners learn nothing inside and come out with no qualifications, no work experience and no realistic goals, so they end up falling back into the same old routine in spite of any initial good intentions. There are no avenues open to them to live a different life.

Channelling aggression

"Without parental guidance or a teacher to spot a talent and egg them on, what hope have they got? They need to be shown how to channel their aggression into something worthwhile. Instead, we've got kids who will kill over a postcode, a girl, a look, all because they want to be noticed. 'Look at me,' they are saying.

"We have to encourage our young people to self-motivate, to believe in themselves, with parents and teachers working together. Instead, we've got parents and teachers blaming each other and teachers speaking to these kids with attitudes like shit."

Young says much more could be done to improve the job prospects for ex-prisoners. "Halving sentences just means career criminals can commit heavier crimes knowing he or she will get a more lenient sentence. It's no deterrent."

"Prisoners need to be made to go to work full time like we do, but there have to be employment opportunities when they come out. Someone has to give them a chance."

He would like criminal justice agencies such as youth offending teams, police, probation and the youth justice board, as well as social services, to work with chambers of commerce to persuade community-minded businesspeople to give ex-offenders a chance.

Young lives, breathes and sleeps Laces, but he does have a dream for his future. "I'd like to be filmed swimming an Olympic length, and then I'd get a mathematician to calculate my speed, take my age into account and work out what it would have been when I was 18 and tell me whether I'd have won a medal."